Endless band stenciling apparatus

ABSTRACT

A stenciling apparatus is provided with a screen formed as an endless band trained about and tensioned on four sprockets and driven by a shaft on which two of said sprockets are mounted. The sprockets are adjustable to vary the longitudinal and transversal tension of the screen. The objects to be printed on are brought into contact with the outer face of one flight of the screen band, while a scraper, in contact with the inner face of said flight, urges printing ink across the screen and onto the object.

United States Patent [72] Inventor Madiane Gilbert De Souza Dias Alfortville, France [21] App]. No. 797,998

[22] Filed Feb. 10, 1969 [45] Patented Aug. 10, 1971 [73] Assignee Societe Vitus Etabl'nsements Vitoux Troyes, France [32] Priority Feb. 8, 1968 [33] France [54] ENDLE$ BAND STENCILlNG APPARATUS 12 Claims, 8 Drawing Figs.

[51] Int. Cl 841113/08 [50] FieldofSearch .1 101/114- [56] References Cited UNITED STATES PATENTS 1,780,095 10/1930 Norman 101/115 Primary Examiner-Clyde 1. Coughenour Attorney- Edwin E. Greigg ABSTRACT: A stenciling apparatus is provided with a screen formed as an endless band trained about and tensioned on four sprockets and driven by a shaft on which two of said sprockets are mounted. The sprockets are adjustable to vary the longitudinal and transversal tension of the screen. The objects to be printed on are brought into contact with the outer face of one flight of the screen band, while a scraper, in contact with the inner face of said flight, urges printing ink across the screen and onto the object.

PATENTEB AUG I 0 I97! SHEET 1 BF 3 INVENTOR MADIANE GILBERT 05 SOUZA DIAS PATENTEU AUBIOIQH 3 59 0 9 SHEET 2 OF 3 DZ 16 17/6 1 a 18 1 /7 i 2/ 22 23 25 PATENTEU Aumolun 3,598,049

SHLU 3 U? 3 on w p 2 u. h" r INVENTOR MADIANE GILBERT DE SOUZA DIAS ATTORNEY ENDLESS BAND STENCILING APPARATUS BACKGROUND OF THE INVENTION they are, together with the screen, temporarily immobilized with respect to the stand of the apparatus while the scraper moves with respect thereto. Cylindrical objects, on the other hand, are rotatably mounted on appropriate journaling means while the screen is moved with respect thereto in a reciprocating motion. In such a case the scraper is, held immobile at the level of the generatrix along which the printing is performed.

Such apparatus is relatively very bulky for given printing lengths, and in case of an apparatus operating with a moving frame, a free horizontal space is required which is at least twice the printing length.

Further, numerous difficulties are encountered in connection with machines of the aforedescribed type in adjusting the longitudinal and transversal screen tension, in supplying the ink or performing maintenance and cleaning operations It is known to provide, for printing on fabrics, a stenciling apparatus which has two rolls mounted on parallel shafts (a driving shaft and an idler) around which there is trained in a tensioned condition a screen formed ofa continuous band. To each edge of the screen there is affixed a band provided with spurs cooperating with gears secured to the ends of the rolls.

A machine of the aforenoted type cannot be utilized for providing prints on objects. Often, the surfaces to be printed on have a nonplanar, usually convex configuration'which has to be slightly enveloped" by the screen in the printing zone where the scraper engages the screen. As a result, the screen is pinched between each of the rolls and the highest points on the object. Further, in each instance, inks generally utilized for the printing on objects are of such a nature that they soil the rolls which, in turn, causes an abundant flow of ink making impossible a fine printing, such as usually required on electronic components.

To be able to use a continuous screen 2 printing on objects it is thus essential to have a screen which does not bear upon any part and the lateral tension of which is adjustable in order to adapt said tension to the shape of the object. Finally, in order to control the starting point of the printing, particularly when a conveyor for the objects is used, it is essential that the scraper be adjustable in its longitudinal position with respect to the conveyor, if used, or with respect to a reference mark on the object in case an object of substantial length is being advanced,

OBJECT AND SUMMARY OF THE INVENTION It is the principal object of the invention to provide an im-- proved stenciling apparatus for printing on objects that is of simple structure and obviates the aforeoutlinerl disadvantages.

Briefly stated, the stenciling apparatus according to the invention is provided, on the one hand, with a driving shaft and an idling shaft spaced parallel therewith, and a sprocket affixed to each end of said shafts in such a manner that two sprocket pairs are formed, wherein the sprockets constituting a pair are coplanar, and, on the other hand, with a screen formed as an endless band, to the two opposed edges of which there are affixed two parallel spaced endless belts trained about the sprockets and tensioned thereby. Further, a scraper is oscillatably and adjustably mounted between the lower and upper flights of the screen band in such a manner as to cooperate with the inner face of said lower flight to force ink through said screen onto the object in contact with the outer face of said lower flight.

The invention will be better understood and further objects as well as advantages will become more apparent from the ensuing detailed specification of a preferred, although exemplary, embodiment taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view from below the printing element of the apparatus with some parts partially torn away;

FIG. 2 is a partly sectional end elevational view of the screen and its driving mechanism as viewed from the left of FIG. 1;

FIG. 3 is a sectional view of a part shown in FIG. 2 taken along line IV-IV thereof;

FIG. 4 is a schematic side elevational view of the screen and its inking mechanism as viewed along line IV-IV of FIG. 2;

FIG. 5 is a schematic view illustrating the particular arrangement of a scraper and a counterscraper;

FIG. 6 is another embodiment of the structure shown in FIG. 2;

FIG. 7 is a view similar to FIG. 4 illustrating another inking means; and

FIG. Sis a perspective view.

DESCRIPTION OF THE PREFERREDEMBODIMENT Turning now to FIG. 1, there is shown a driving shaft l actuated by any convenient motor'means (not shown) andan idling shaft 2 parallel spaced from" the driving shaft 1. These shafts are held suspended in two bearing pairs 3 and 4 attached respectively to two carriages 5 and 6 which are inde- On one end of shafts 1 and 2, respectively, there are mounted sprockets 11 and 12, adjustable along their respective shafts for the purpose vof aligning them to assume a coplanar relation. Shafts 1 and 2 carry on their respective opposed ends sprockets 13 and 14 mounted adjustably in a manner hereinafter described and also adapted to assume a coplanar position with respect to one another.

Each sprocket 1l14 has radially outwardly projecting teeth 15 and is provided, as best seen in FIG. 2, with two lateral flanges 16 and 16a. The teeth 15 are adapted to cooperate with two toothed endless belts 17, one trained about sprockets 11 and 12, while the other is trained about sprockets l3 and 14. The belts 17 are, at their outer face, bonded to the inner face of two opposed edges of a screen 18, which is anendless band made of silk, nylon, stainless steel or any other material adapted to be used for a stenciling screen.

The adjusting means for sprockets 11, 12 are not shown; they may be of any known structure.

The sprockets l3 and 14 are very accurately adjustable on shafts 2 and 1, respectively, by means of devices, one ofwhich is shown in axial section in FIG. 2 and in cross section in FIG. 3. Sprocket 13 carries a central bearing member 19 provided with a radially extending slot 20 cooperating with a key 21 disposed longitudinally on shaft 2 and firmly affixed thereto. Thus, the sprocket 13 is prevented from rotating with respect to shaft 2, but is free to slide axially thereto within the limit of the length ofthe key 21.

To the sprocket 13 there is affixed a sleeve 22 and two diametrically-opposed parallel pull rods 23 which pass through a cover plate 24 and carry at their end two nuts 25 which urge the coverplate 24 against the outer terminal edge of sleeve 22.

The cover plate 24 is provided with a central opening 26a in which there is threadedly engaged an axially extending threaded rod 26 provided at its outer end with a hand wheel 27.

The apparatus is further provided with a scraper 28 pivotally secured to one of the carriages 5 or 6 between the two flights of the screen 18 and with a counterscraper 29 whichensures the uniformity of the thickness of the ink layer and prevents the ink spread by the scraper 28 from flowing over the lateral edges of the screen 18. For this purpose, the counterscraper 29 is provided at its end with two bent deflectors 30 and 3!. This device is illustrated in FIGS. 4 and 5 in which the motion of the screen 18 is indicted by respective arrows F and F 7 The apparatus is also provided with an ink recovering blade 32 which is normally disposed, as in FIG. 4 shown at 32', with broken lines, and may be lowered to a working position as shown in the same figure at 32 with solid lines. It is thus seen that when the driving shaft rotates while the scraper 28 is lifted and the ink recovering blade 32 is lowered, the ink automatically accumulates at the lower portion of blade 32.

OPERATION OF THE EMBODIMENT After setting the sprockets 11 and 12 into an approximately proper position to accommodate a screen 18 of given width, the two shafts 1 and 2 are moved towards one another by manipulating at least one of the hand wheels 9 or 10. Thereafter, the screen 18 is pulled over the sprockets and one of the belts 17 is brought into a meshing engagement with its associated sprocket II, 12. Thereafter, by rotating the threaded rod 26 in the proper direction by means of hand wheel 27, the sprockets l3 and are first adjusted in'such a manner as to bring them into interengaging, meshing relationship with the other belt 17.

Thereafter, the spacing between shafts 1 and 2 is adjusted, for example, by means of hand wheel 9 so as to properly tension the screen 18 in a longitudinal direction after having positioned, by means of the hand wheel 10, the scraper 28 to the level of the starting line for the printing, that is, in alignment with the axis of the first object-conveyor if cylindrical objects are involved. Then, in a second adjusting phase of sprockets I3 and 14, they are shifted by turning the threaded rod 26 with v the aid of hand wheel 27 in such a manner as to transversely tension the screen 18. This transversal tensioning is effected by the internal flanges 16 engaging the internal edge of the belt 17. It is to be noted that the'flanges 160, which are useful at the beginning for the initial positioning of the screen, may be omitted altogether.

Thereafter, the screen is provided with a suitable quantity of ink and the scraper 28 and ink recovery blade 32 are set into their respective printing position. Then, the apparatus is set in motion and the objects (such as bottles, for example) are brought into alignment with the scraper 28 on conventional conveying means.

In the example shown, the scraper 28 and the counterscraper 29 are mounted on the carriage 6 in such a manner that by manipulating jointly the carriages 5 and 6, it is always possible to easily adjust the printing position.

Once this adjustment is performed, it is desirable to automatically find again this setting after the carriages 5 and 6 are brought closer with respect to one another, for example, for removing the screen 18 for cleaning purposes. To this end, threaded rods 33 and 34 are provided which cooperate with corresponding threaded openings provided in the table 7 and carry control knobs 35, 36 and locking nuts 37, 38.

MODIFICATION OF THE PREFERRED EMBODIMENT.

FURTHER FEATURES AND ADVANTAGES FIG. 6 illustrates a modified embodiment of the screen. Here, a screen 40, which is similar to screen 18 and which carries at its edges toothed driving belts 41, is provided with a base 42 made of spongy material adapted to be impregnated with suitable printing ink. The shaft 43 carries sprockets (only one shown at 44) of a structure similar to those of sprockets 1114. About sprockets 44 there is trained and tensioned an endless band 46 made of an impervious flexible material cooperating with the said sprockets by means of toothed belts 45. This assembly is dimensioned in such a manner that in an operating position the band 46 extends in the immediate vicinity of the internal face of the base 42.

When the machine is in operation, it is sufficient to impart to the upper face of the lower flight of band 46 a suitable pressure, for example, by means of a spatula or a roller, neither shown, to effect the passage of the ink through the screen 40.

The aforenoted embodiment may be further developed by dividing the base 42 into zones such as 42a, 42b and 42c, separated by an impervious flexible partition 50 to permit multicolor printing in a single pass. The zones 42a, 42b and 420 may be easily filled with inks of different colors after the screen 40, together with base 42, is removed from the apparatus.

According to a further embodiment illustrated in FIG. 7, instead of a scraper, the inking is effected by an inking roll 47 made of a spongy material which may be impregnated with ink either prior to its insertion into the apparatus or may be inked in a continuous manner by a distributing conduit 48.

It is to be noted that a screen formed of an endless band in accordance with the invention may be provided at the outer face each of its edges with a belt 49 (FIG. 6) made of rubber or similar material and adapted to be brought into engagement by virtue of its face spaced from and parallel to the screen with the object in such a manner as to cause or aid its rotary motion. This arrangement is also useful when printing has to be effected longitudinally with respect to heavy and long objects. In such a case the assembly is shifted manually on the object, whereby the bands 49 have the role of caterpillar tracks and the rotation of the screen is effectuated synchronously with its linear advance. In this manner a portable stenciling apparatus is obtained which prints automatically and which may be utilized in various locations.

An apparatus according to the invention is advantageous in that it permits a very rapid printing since there are no parts that move with a reciprocating motion during operation. Further, since the printing element is made of an endless belt, the spatial requirements are reduced by more than half compared to machines operating with conventional screens. In case of printing on cylindrical objects, the reduction in size is even more substantial since the machines operating with conventional screens must have, as noted hereinbefore, a space approximately twice the longitudinal dimension of the screen which reciprocates under the scraper.

It is further to be noted that the apparatus according to the invention may be void of any mechanical elements below the plane of printing; this fact substantially increases the possibilities of application and the facility of utilization.

Thus, when the table 7 is pivotally mounted on a stand 51 (FIG. 8) resting on the ground, printing may be performed on vertically, obliquely, or horizontally disposed objects. The table 7, however, may be attached to a suspended support which permits the printing on any zone of a very large object, such as a metal sheet.

It is to be understood that the apparatus described, regardless of its actual structure, may use either a screen obtained by joining the ends of a conventional rectangular screen or a continuous, seamless screen made of a tubular material. In the latter case, the text or design from a printing plate or the like is applied by illumination in a known manner while the screen is tensioned on a rotary support constituted by two coaxial sprockets, the spacing of which may be adjusted. The machine described may be used for sensitizing; an assembly similar to that shown in FIG. 6 may be used for effectuating light exposure. For this purpose all that needs to be A. a screen formed as an endless band having 1. toothed means along opposed edges thereof,

2. continuous projecting means affixed to said endless band along opposed edges thereof, said continuous projecting means defining a continuous edge face extending substantially normal to said endless band,

B. a drive shaft,

C. an idling shaft disposed parallel with said drive shaft,

D. means for adjusting the distance between said shafts,

E. two sprockets mounted on said drive shaft,

F. two sprockets mounted on said idling shaft, said screen adapted to be trained about said shafts while said toothed means mesh with said sprockets,

G. flange means affixed to each sprocket and defining a radial face extending parallel to and being in contact with said continuous edge face; said flange means exerting a transversal tension to said screen through said projecting means,

H. means for axially adjusting at least one sprocket on each of said shafts for varying said transversal tension, and

I. inking means disposed between two flights of said screen trained about said shafts for providing ink across said screen to an object moving relatively thereto.

2. The improvement as defined in claim 1, including two parallel spaced endless belts bonded at their outer face to the inside of said screen along the edge or marginal regions thereof, the other face of said endless belts is provided with teeth cooperating with said sprockets and constituting said toothed means, each endless belt having a lateral edge constituting said continuous edge face.

3. The improvement as defined in claim 1 including means that prevents said sprockets from rotating with respect to their shafts, but permits said sprockets to be displaced axially thereon.

4. The improvement as defined in claim 1, wherein said inking means includes a scraper in engagement with an inner face ofsaid screen and adapted to force ink therethrough.

5. The improvement as defined in claim 1, wherein said inking means includes a spongy base secured to and extending along the inner face of said screen.

6. The improvement as defined in claim 5, wherein said spongy base is formed of a plurality of zones separated from one another by impervious, flexible partitions.

7. The improvement as defined in claim 5 including an endless flexible impervious band extending immediately adjacent and parallel with said base and supported by sprockets mounted on said shafts.

8. The improvement as defined in claim 1 including two endless belts bonded to the outer face of said screen along its two opposed edge or marginal regions, said last-named endless belts having work faces parallel with and spaced from said outer face to engage said objects.

9. The improvement as defined in claim 8, wherein said lastnamed endless belts are made of rubber.

10. An improvement as defined in claim 1, including A. a table,

B. two carriages, one supporting said drive shaft, the other supporting said idling shaft,

C. mounting means for movably securing said carriages to said table, and

D. adjusting means for moving either carriage with respect to said table independently from the other.

11. An improvement as defined in claim 10, including A. a machine frame, and

B. means for pivotally securing said table to said machine frame to adjust at will the inclination of said table with respect to said machine frame.

12. An improvement as defined in claim 4, including A. a table,

B. two carriages, one supporting said drive shaft, the other supporting said idling shaft,

C. mounting means for movably securing said carriages to said table,

D. adjusting means for moving either carriage with respect to said table independently from the other, and

E. means for pivotally securing said scraper to one of said carriages. 

1. In a stenciling apparatus particularly for printing on objects, the improvement comprising, A. a screen formed as an endless band having
 1. toothed means along opposed edges thereof,
 2. continuous projecting means affixed to said endless band along opposed edges thereof, said continuous projecting means defining a continuous edge face extending substantially normal to said endless band, B. a drive shaft, C. an idling shaft disposed parallel with said drive shaft, D. means for adjusting the distance between said shafts, E. two sprockets mounted on said drive shaft, F. two sprockets mounted on said idling shaft, said screen adapted to be trained about said shafts while said toothed means mesh with said sprockets, G. flange means affixed to each sprocket and defining a radial face extending parallel to and being in contact with said continuous edge face; said flange means exerting a transversal tension to said screen through said projecting means, H. means for axially adjusting at least one sprocket on each of said shafts for varying said transversal tension, and I. inking means disposed between two flights of said screen trained about said shafts for providing ink across said screen to an object moving relatively thereto.
 2. continuous projecting means affixed to said endless band along opposed edges thereof, said continuous projecting means defining a continuous edge face extending substantially normal to said endless band, B. a drive shaft, C. an idling shaft disposed parallel with said drive shaft, D. means for adjusting the distance between said shafts, E. two sprockets mounted on said drive shaft, F. two sprockets mounted on said idling shaft, said screen adapted to be trained about said shafts while said toothed means mesh with said sprockets, G. flange means affixed to each sprocket and defining a radial face extending parallel to and being in contact with said continuous edge face; said flange means exerting a transversal tension to said screen through said projecting means, H. means for axially adjusting at least one sprocket on each of said shafts for varying said transversal tension, and I. inking means disposed between two flights of said screen trained about said shafts for providing ink across said screen to an object moving relatively thereto.
 2. The improvement as defined in claim 1, including two parallel spaced endless belts bonded at their outer face to the inside of said screen along the edge or marginal regions thereof, the other face of said endless belts is provided with teeth cooperating with said sprockets and constituting said toothed means, each endless belt having a lateral edge constituting said continuous edge face.
 3. The improvement as defined in claim 1 including means that prevents said sprockets from rotating with respect to their shafts, but permits said sprockets to be displaced axially thereon.
 4. The improvement as defined in claim 1, wherein said inking means includes a scraper in engagement with an inner face of said screen and adapted to force ink therethrough.
 5. The improvement as defined in claim 1, wherein said inking means includes a spongy base secured to and extending along the inner face of said screen.
 6. The improvement as defined in claim 5, wherein said spongy base is formed of a plurality of zones separated from one another by impervious, flexible partitions.
 7. The improvement as defined in claim 5 including an endless flexible impervious band extending immediately adjacent And parallel with said base and supported by sprockets mounted on said shafts.
 8. The improvement as defined in claim 1 including two endless belts bonded to the outer face of said screen along its two opposed edge or marginal regions, said last-named endless belts having work faces parallel with and spaced from said outer face to engage said objects.
 9. The improvement as defined in claim 8, wherein said last-named endless belts are made of rubber.
 10. An improvement as defined in claim 1, including A. a table, B. two carriages, one supporting said drive shaft, the other supporting said idling shaft, C. mounting means for movably securing said carriages to said table, and D. adjusting means for moving either carriage with respect to said table independently from the other.
 11. An improvement as defined in claim 10, including A. a machine frame, and B. means for pivotally securing said table to said machine frame to adjust at will the inclination of said table with respect to said machine frame.
 12. An improvement as defined in claim 4, including A. a table, B. two carriages, one supporting said drive shaft, the other supporting said idling shaft, C. mounting means for movably securing said carriages to said table, D. adjusting means for moving either carriage with respect to said table independently from the other, and E. means for pivotally securing said scraper to one of said carriages. 